Sui Lutris: An efficient Blockchain solution that combines DAG Consensus and non-consensus methods.

Blockchain technology has made significant progress since the birth of Bitcoin. With the emergence of new application scenarios such as gaming and NFTs, the Blockchain Community is exploring ways to improve technical efficiency, particularly in handling high loads and real-time latency. L1 Blockchains face two major challenges: first, the need to achieve high throughput while maintaining low latency, and second, ensuring the long-term stability of the consensus protocol. In addressing these challenges, it is also important to maintain decentralization through the dynamic participation and reconfiguration of verification nodes.

One way to increase throughput is to use a DAG-based Consensus protocol. Such protocols allow the Blockchain to process a large number of transactions simultaneously, making them very suitable for applications like games and NFTs. However, DAG-based protocols may lead to latency of a few seconds, which can be costly for regular transfers or gaming operations.

On the other hand, non-consensus protocols show great potential in reducing latency and scalability. These protocols do not require consensus, allowing for the rapid processing of transactions without the need for global ordering of independent transactions that are processed in parallel. However, they are limited to a class of constrained simple blockchain operations, which restricts the smart contract functionalities that can be achieved, and reconfiguring a dynamically changing set of validators may be challenging.

Despite the potential of these methods, none have been used in production-level Blockchain yet; they have only been presented at academic conferences and have not been widely adopted by the Blockchain Community. Sui Lutris is a supporting protocol that combines DAG-based Consensus and non-consensus methods, achieving the best of both worlds: sub-second latency and sustained throughput of thousands of transactions per second. It also maintains the ability to express complex contracts on shared objects, generate checkpoints, and reconfigure the validator set across periods.

Sui Lutris adopts a unique approach that combines the two aforementioned solutions. To ensure the security of asset operations for a single owner, the system employs a consistent broadcasting protocol among validators, achieving latency below consensus. Sui Lutris relies solely on consensus to process complex smart contracts on shared objects. It also supports network maintenance operations, such as defining checkpoints and reconfiguring validators. This new strategy provides a win-win solution when handling transactions in a replicated Byzantine environment.

In Sui Lutris, users who have private keys create and sign transactions to change the objects they own or mix objects. Transactions are sent to each validating node, which performs validity and security checks, and returns the signed transaction to the client. The client collects responses from the majority of validating nodes to form a transaction certificate, at which point the transaction is considered irreversible. Once the certificate assembly is complete, it is sent back to all validating nodes for confirmation. Transactions involving exclusive objects can be executed immediately, without waiting for the consensus engine. All certificates are forwarded to the DAG-based consensus protocol. The consensus ultimately outputs the total order of certificates; validating nodes check and execute transactions that include shared objects. Clients can collect responses from the majority of validating nodes, assembling them into effect certificates as proof of transaction settlement. Subsequently, a checkpoint is formed for each consensus submission to drive the reconfiguration protocol.

In addition to the main trading process, Sui Lutris also provides multiple facilities to support production-level Blockchain:

1. Implement a checkpoint protocol to generate the causal history of all transactions in the system for complete auditing and efficient synchronization.

2. Support for reconfiguration at the end of each period, the validator set and their voting power may change.

3. Safely "unlock" mistakenly locked assets at the end of the epoch to minimize vulnerability damage.

Sui Lutris supports blockchain management of large amounts of value. The full technical report provides details on the operation of security and liveliness protocols, as well as security proofs with partially synchronous Byzantine participants in a standard distributed system model.